I just put on some new hooker headers and flowmaster super10s truck sounds great but has powers loss at high rmp' s and backfires at idle every now and then never happened before exhaust pipe is 2.5 inches on everything engine is a 360 HELP FAST!!!!!!

 

so did you run true duels or is there some type of y-pipe?

 

Since the engine is able to breath better you might play with the timing and fuel mixture a little.

 

I would double check your plug wires for being on the correct plug.

 

Yeah i ran true duals on it but the muffler shop didnt put in any h pipe or x pipe to help with the flow between the 2 engine banks i can almost bet thats were the problem is coming from and i checked all plug wires for proper placement.

 

you notice any power loss?

 

only power loss was when i really stomped on the gas found out the cable for the choke was stuck about half closed so i took it off lol a little hard to start when its cold now but well worth it.

 

^ I agree

Also an H-pipe would benefit low end torque some.